1. Field of the Invention
This invention relates to a flow controller located at the base of a hopper in a hold of a self-unloading ship and in particular, to a flow controller that controls the flow of particulate material from said hopper and can be made water-tight when in a closed position.
2. Description of the Prior Art
Hydraulically-operated hopper gates for self-unloading ships are known. U.S. Pat. No. 4,004,700 naming Empey as inventor describes a gate that is divided into two horizontal segments that are mounted on tracks and hydraulically controlled to move horizontally along the tracks between a closed and open position.
U.S. Pat. No. 3,601,268 naming Bethge, et al. as inventors describes what purports to be a water-tight gate for use in the hold of a ship having a continuous conveyor belt. In a closed position, a lower gate section and an upper gate section come together with the conveyor belt in between. In U.S. Pat. No. 4,428,504 naming Bassett, et al. as inventors, a gate assembly has inflatable seals to prevent the escape of lumped material from the hopper as well as effectively preventing water or other fluids from being introduced into the hopper. Previous gates are not water-tight or use inflatable seals that tend to leak or deflate with time, or require a constant supply of pneumatic pressure, or require the use of plugs in addition to the gate, or are not water-tight, or do not permit the conveyor to be used unless all of the gates have been opened, or they are expensive, or complex, or they leak as the gate wears, or as the seals become worn by particulate material being discharged from the gate. See also U.S. Pat. No. 4,574,989 naming Charles D. Pole as inventor.